We propose to develop a new technology to address the need for a routine clinical method to preserve tissue for cytochemical assay. The new technology addresses the fact that frozen specimens are preferred for bioactivity, but available methods give inaccurate data. The method LYOPHILM combines lyophilization and FREEZE-TRANSFER to form a method in which thin sections of frozen tissue are thaw-mounted as a pathologically coherent set onto a TISSUE DISC, which is a flexible plastic laminate comprising microporous thin films (windows) coated with a surfactant gel blend. This thin film/surfactant construct permanently bonds tissue and forms a functional interface through which water is transferred into the film, wherein dissolved solutes are immobilized in a cytocoherent pattern. Lyophilization is used to fix and dehydrate tissue non- chemically, and to microchannel tissue to normalize regional density differences and enhance target access to reactants. In Phase 1, we propose to validate the method in head to head Performance testing with competing methods for storage of frozen breast tissue at above freezing temperatures for two years. Performance will be assessed by quantitative assays of cytocoherent preservation of estrogen receptor and Her-2 immunoreactivity. In Phase 2, we will develop the hardware for automated specimen storage and retrieval and develop methods to extend above- freezing storage to five years. The technology is designed for incorporation into an integrated system of automated analytical cytochemistry in which we anticipate polymeric films will replace nonporous glass as tissue substrates.